Project Summary Gastrointestinal (GI) cancer, a major public health concern, is the second leading cause of cancer death in developed countries with a much higher incidence in obese and diabetic patients. The emerging view suggests that understanding the symbiotic relationship between diet, microbial metabolism and GI cancer should be considered in order to better predict and prevent cancer progression. Accumulating evidence suggests the short-chain fatty acids acetate, propionate and butyrate function in the suppression of inflammation and cancer, whereas other metabolites, such as secondary bile acids, promote carcinogenesis. Thus, it is important to develop more effective methods for early diagnosis of this disease process, assess disease severity, and prognosticate course. With increasing focus on metabolites as potential biomarkers with most closely related to a cancer phenotype, they can provide clinically useful tools and may open new avenues for diagnostics. Based on the experience gained during the sabbatical year at UC Davis, this application proposes to explore the role of diet on GI cancer using NMR-based metabolomics applied to the animal model. Accordingly, this project will focus on a specific research objective to test the hypothesis: the excess cholesterol found in a Western diet (high fat and high sugar) results in chronic exposure to high levels of hydrophobic toxic bile acids, and thereby contributes to the development of GI cancer. To address this broader issue, we undertake a reductionist approach by a collaborative strategy that utilizes a nuclear magnetic resonance (NMR) based metabolomic measurement in conjunction with other ongoing studies on functional genomics, proteomics, as well as the microbiota profile. An optimal experimental design that leverages the PI's expertise in spectroscopic aspects of NMR is proposed. In an animal model to test for cause-and-effect, we propose to study the role of diet using bile acid receptor knockout (FXR KO) mice coupled with an NMR metabolomics approach. This proposal is significant because it seeks to reveal the molecular mechanism between diet and GI cancer using an NMR-based metabolomic approach in a robust animal model. Outcomes may directly impact the selection of small molecule pharmacologic tools to better understand human malignancies.